Diesel hammer

ABSTRACT

The present invention provides a diesel hammer having as major structural parts a cylinder whose upper end is opened, a ram slidably fitted into said cylinder, an anvil fitted into the lower end of said cylinder, and a fuel tank, a fuel pump and nozzles mounted upon the outer surface of said cylinder. A port is formed through said cylinder so as to deliver the air under pressure from the cylinder to said fuel pump and to deliver the fuel in said fuel tank to said nozzles.

United States Patent Inaba et a1. [45] July 25, 1972 [54] DIESEL HAMMER [56] References Cited [72] Inventors: Kohsaku lnaba; Selsaku Yoshida, both of UNITED STATES PATENTS Tokyo; Shoji Matsuura; Tsukasa' Murakami, both f Yokohama a" f Japan 2,093,634 9/1937 Cordes ..l73/ 137 X 2,633,832 4/1953 Spurlin..... .123/46 SC X 1 -a IshikawmimI-Harlm aw Kabushlki 2,755,783 7/1956 Kupka ..l23/46 Kaisha, T y 1 2,792,816 5/1957 Oyer ..l73/l36 x [22] Filed. Oct 19, 1970 2,804,856 9/1957 Spurlin ..173/ 135 X 2,948,122 8/1960 Smith ..l73/l37 X [21] Appl. No.: 82,041

Primary Examiner-David H. Brown [30] Foreign Application Priority Data Am1mey-N0he None Oct. 24, 1969 Japan... .....44/85078 57 ABSTRACT Oct. 24, 1969 Japan... .....44/85079 j 0m. 24, 1969 Japan ..44/85080 The Present mvenllon pwvldes dlesel hammer havlns as major structural parts a cylinder whose upper end is opened, a ram slidably fitted into said cylinder, an anvil fitted into the U-S. lower end of said cylinder and a fuel tank a fuel pump and [51] Int. Cl ..E02d 7/12 nozzles mounted upon the outer surface f said |i A [58] Field of Search ..l73/l35, I28, I36, I37; pon is formed through Said cylinder so as to denver the i 123/46 R, 46 SC, 46 H under pressure from the cylinder to said fuel pump and to deliver the fuel in said fuel tank to said nozzles.

5 Clalns, 17 Drawing Figures Patented July 25, 1972 9 Sheets-Sheet 1 2 PRIOR ART PRIOR ART I INVENTORS KOHSAKU INABA SEISAKU YOSHIDA SHOJI MATSUURA TSUKASA MURAKAM/ ATTORNEYS FIG. 4 t

i II

X l Q N 9 I2 10 g 15 II M g I l I 7 I 4 I O I I4 8 (8) I I III I l l 11 I INVENTORS KOHSAKU INABA SEISAKU YOSHIDA SHOJI MATSUURA TSUKASA MURAKAMI BY ATTORNEYS Patented July 25, 1972 3,679,005

9 Sheets-Sheet 4 INVENTORS K AK ABA SEI KU SH Jl MATSUU KASA MURAKAMI ATTORNEYS Patented July 25, 1972 9 Sheets-Sheet 5 INYVENTORS KOHSAKU INABA SEISAKU YOSHIDA SHOJI MA TSUURA TSUKASA MURAKAMI 7/256 3 7 ATTORNEYS Patented July 25, 1972 9 Sheets-Sheet 6 INVENTORS KOHSAKU INABA SEISAKU YOSHIDA SHOJI MATSUURA TSUKASA MURAKAMI 7w;

ATTORNEYS Patented July 25, 1972 9 Sheets-Sheet 8 FIG. /4

FIG. l3

M S A m mM T BHUWH ASU MNOS V M wwmm m wm HS oflww KSST A T TORNE Y3 Patented July 25, 1972 3,679,005

9 Sheets-Sheet 9 I NVENTORS KOHSAKU INABA SEISAKU YOSHIDA SHOJI MATSUURA TSUKASA MURAKAMI ATTORNEYS DIESEL HAMMER DETAILED EXPLANATION OF THE INVENTION The present invention relates to a diesel hammer having an improved efficiency and a strong impact force for driving a pile because of a better combustion.

The conventional diesel hammers may be classified into a diesel hammer of the type in which the fuel is atomized by the impact and a diesel hammer of the type in which the fuel under high pressure is injected, thereby atomizing the fuel.

FIG. 1 is a sectional view of the former type diesel hammer.

FIG. 2 is a sectional view of the latter type diesel hammer.

FIG. 3 is a detailed view of a fuel pump thereof and FIG. 3a is a detailed view of a nozzle for use with the fuel pump of FIG. 3.

Referring to FIG. 1, an anvil 103 is fitted into the lower end of a cylinder 101 while a ram 102 is slidably fitted into the upper portion of the cylinder 101. A fuel tank 104 is fitted over the cylinder 101 and a lever 105 is disposed outwardly of the cylinder 101. A fuel pump 106 comprises an oil chamber 107, a fuel port 108, a valve 109, a connecting rod 110 extending upwardly, etc. When the connecting rod 110 is forced downwardly, a plunger is actuated so that the port 108 is closed while the valve 109 is forced downwardly whereby the fuel in the oil chamber 107 is mechanically dropped through a fuel injection port 111 formed through a wall of the cylinder 101 into a concave surface 115 of the anvil 103. The fuel pump 106 is intercommunicated with the fuel tank 104 through a fuel pipe 112. An opening 113 through which the lever 105 extends inwardly of the cylinder 101 and a suctionexhaust port 114 are formed through the cylinder 101. When the ram 102 drops, it pushes the lever 105 outwardly so that the fuel pump 106 is mechanically actuated, thereby dropping the fuel into the concave surface 115 of the anvil 103. Next the suction-exhaust port 114 is closed by the ram 102. As the ram 102 drops, the air in the cylinder 101 is compressed and when the ram 102 strikes the anvil 103, the mixture is compressed and ignited in a space defined by the concave surface 115 of the anvil 103 and a convex surface 116 of the ram 102. In consequence, the ram 102 is lifted to a predetermined height, thereby completing one cycle of pile driving. This cycle may be automatically repeated in a manner as described hereinabove.

In this type of the diesel hammer, when the ram 102 strikes the anvil 103, the combustion of the mixture is immediately started when the diesel hammer is first started so that the temperature of the structural parts is low. But when the temperature and especially the temperature of the concave surface 115 of the anvil 103 is raised, a part of the fuel may be vaporized so that the combustion starts before the ram 102 strikes the anvil 103. The air pressure in the cylinder 101 is increased higher than that attained by the adiabatic compression of the air so that the downward movement of the ram 102 is much retarded or braked. Therefore, the velocity of the ram 102 at which it strikes the anvil 103 is reduced so that the pile driving efficiency of the diesel hammer is much decreased. When the diesel hammer of the type described is continuously used, the pile driving efficiency is reduced more and more and this reduction in efficiency cannot be prevented. Furthermore, a suitable clearance must be provided between the inner wall of the cylinder 101 and the ram 102 so that the latter may slide in the former. In consequence, the convex surface 116 at the lower end of the ram 102 cannot completely coincide or mate with the concave surface 115 of the anvil 103 when the ram 102 strikes the anvil 103. Therefore, the injected fuel concentrates at some portions of the combustion chamber and the desired atomization of the fuel cannot be attained, whereby the efiiciency is very low.

In the diesel hammer of the type illustrated in FIG. 2, the anvil 103 is fitted into the lower end of the cylinder 101 and the ram 102 having piston rings 118 and 118' fitted therearound is fitted into the upper portion of the cylinder 101. The upper end of the cylinder 101 is closed by a cover 119 so that an air chamber 120 is defined between the ram 102 and the cover 119. The fuel pump 106 comprises a spring 121 in a main body, a member 122 for supporting and guiding the spring 121, a plunger 123, a cylinder 124, a discharge valve 125, a discharge valve spring 126, a fuel port 127 and a connecting or actuating rod 128 extending beyond the upper end of the fuel pump 106. When the rod 128 moves downwardly the plunger 123 also moves downwardly against the spring 121, thereby discharging the fuel. A nozzle 129 comprises a fuel injection orifice 130 formed through the leading end of the main body, a nozzle tip 132 having a fuel oil chamber 131, a valve 133, a spring 134 for supporting the valve 133 and fuel ports 13S and The fuel is therefore injected into the cylinder 101 through the port 130 when the valve 133 is opened. Thus, the fuel in the fuel pump I06 may be injected through the fuel passage 136 and nozzle 129 into the combustion chamber 117. The lever 105 for actuating the fuel pump 106 mechanically is rotatably fixed to the cylinder 101 above the fuel pump 106. The lever 105 is actuated by the downward movement of the ram 102 so that the rod 128, the plunger 123, and the member 122 move downwardly. The fuel below the plunger 123 is forced downwardly while the plunger 123 closes the port 127 and the fuel forced into the passage 136 is then forced into the oil chamber 131 of the nonle tip 132 through the ports 135 and 135' of the nozzle proper 129. The valve 133 is opened against the spring 134 and the fuel is injected and atomized through the orifice 130 of the nozzle tip 132 into the combustion chamber 117 above the anvil 103.

In the diesel hammer of the type described hereinabove, the fuel injection pressure is produced when the ram 102 engages with the lever 105 so that all of the fuel is forced to be injected into the combustion chamber 117 during the downward stroke of the ram 102 so that combustion tends to start before the ram 102 strikes the anvil 103. Therefore, the downward movement of the ram 102 is braked or retarded as in the case of the diesel hammer described with reference to FIG. 1. The efficiency is of course decreased.

One illustrative embodiment of the present invention will be described with reference to the accompanying drawings in which:

FIG. 4 is a side view partly in section of a diesel hammer in accordance with the present invention; FIG. 5 is a fragmentary sectional view thereof illustrating the ram striking the anvil; FIG. 6 is a horizontal sectional view illustrating the direction of the fuel spray from the nozzles; FIG. 7 is a horizontal sectional view illustrating the direction of the fuel spray from the nozzles; FIG. 8 is a fragmentary sectional view illustrating the direction of the air flows; FIG. 9 is a horizontal sectional view illustrating the direction of the air flows; FIGS. 10 and 11 are horizontal sectional view illustrating the flow of the sprayed fuel; FIG. 12 is a detailed view of the fuel pump and FIG. 12a is a detailed view ofa nozzle for use with the fuel pump of FIG. 12; FIG. 13 is a vertical sectional view of a diesel hammer pro vided with a device for stopping the operation thereof; FIG. 14 is a detailed view of one embodiment ofa device for stopping the operation ofthe diesel hammer; and FIG. 15 is a view illustrating another embodiment of the device for stopping the operation.

Referring to FIG. 4, the anvil 3 is fitted into the lower end of the cylinder 1 and the ram 2 having piston rings 4 and a portion reduced in diameter at the lower portion thereof (to be referred to as the reduced portion" hereinafter) is slidably fitted into the upper portion of the cylinder 1. A combustion chamber 5 is defined by the cylinder 1, the anvil 3, and the ram 2 as shown in FIG. 5. A fuel tank 6 is fixed to the center periphery of the cylinder 1 and a fuel pump actuable under the pressure of the air inside the cylinder 1 is disposed below the fuel tank 6. A joint 9 for branching the fuel lines is disposed at a suitable position below the fuel tank 6. A pair of fuel injection nozzles 8 and 8' are disposed in diametrically opposed relation with each other so as to inject the fuel into the combustion chamber 5. A suction-exhaust port 15 is formed through the cylinder wall and an air port 14 is also formed through the cylinder wall substantially at the center of the combustion chamber 5 so as to deliver the air pressure inside the cylinder 1 to the fuel pump 7. A fuel line intercommunicates between the fuel tank 6 and the fuel pump 7, which in turn is communicated to the joint 9 through a fuel line 11. The joint 9 is communicated with the nozzles 8 and 8 through fuel lines 12 and 13 respectively. The air is compressed when the ram 2 closes the suction-exhaust port 15 and drops toward the anvil 3 and is delivered to the fuel pump 7 so as to actuate it, thereby delivering the fuel received from the fuel tank 6 to the nozzles 8 and 8' through the joint 9.

As described hereinabove, the nozzles 8 and 8' are diametrically opposed in the combustion chamber 5 and their orifices are directed toward the center of the chamber 5. That is, the injection orifice of each of the nozzles 8 and 8' may be so designed that the fuel may be sprayed at an angle of a in both sides of the line connecting the orifices of the nozzles 8 and 8' and the center of the cylinder 1 as shown in FIG. 6. Alternatively, the fuel may be sprayed only in one direction relative to the line a at an angle a as shown in FIG. 7.

The fuel pump 7 may be fixed to the cylinder 1 by bolts 16. FIG. 12 is a detailed view of the fuel pump 7. The pump 7 comprises a cylinder 23 actuable by the air (to be referred to as the pneumatic cylinder" hereinafter) and fixed to the cylinder 1 by bolts (not shown), a stopper 22 disposed above the pneumatic cylinder 23 for limiting the upper end of the stroke or movement of a pneumatic piston to be described hereinafter and also serving as a guide for a push rod to be described hereinafter, a fuel pump body 21 assembled into a unitary construction above the stopper 22, an air passage 24 formed in the lower portion of the pneumatic cylinder 23 in communication with the air port 14, the pneumatic piston 26 which is U-shaped in cross section and provided with piston rings 25 and fitted into the pnuematic cylinder 23, and the push rod 27 which is vertically slidably fitted into the stopper 22 in such a manner the lower end of the push rod 27 may be positioned within the pneumatic piston 26.

When the piston 26 is moved upwardly by the air under pressure (delivered from the combustion chamber 5 through the port 14 and the passage 24), the push rod 27 is also moved upwardly through the stopper 22 which serves as a guide. An oil chamber 28 is formed in the pump body 21 into which is fitted a pump cylinder 30 having a lateral fuel passage 29. A pump plunger 31 is vertically slidably fitted into the pump cylinder 30 and an oil chamber 32 is formed above the pump plunger 31. A pump spring guide 33 is vertically slidably fitted into the pump body 21 in such a manner that the guide 33 may support the lower end of the plunger 31 and may be made in contact with the upper end of the push rod 27. A pump spring 34 is interposed between the guide 33 and the inner wall of the pump body 21. The fuel in the fuel tank is delivered into the oil chamber 32 of the plunger 31 through the fuel line 10, the oil chamber 28 and the fuel passage 29. A plug screwed into the upper end of the pump body 21 has a fuel passage 37 and a valve which is pushed downwardly under the force of a valve spring 36.

When the plunger 31 closes the fuel passage 29 and rises further, the fuel in the oil chamber 32 is compressed so that the valve 35 is opened, thereby forcing the fuel into the fuel lines11, 12 and 13.

FIG. 12 is a detail view of the fuel injection nozzles 8 and 8. A nozzle tip 42 having an injection orifice 39 and oil chambers 40 and 41 is fixed to the leading end ofa nozzle holder 38. A needle valve 43 is slidably fitted into the nozzle tip 42 and is normally pressed against a valve seat 45 by a valve spring 44 so as to isolate the oil chambers 40 and 41 from each other. The spring 44 may have a constant force or its force may be adjustable by a screw or the like. The spring 44 is disposed within the nozzle holder 38 as shown in FIG. 12. The fuel passages 46, 47 and 48 are formed in order to deliver the fuel from the fuel lines 11, 12 and 13 to the oil chamber 40. When the fuel is delivered into the oil chamber 40, the needle valve 43 is opened against the spring 44 so that the fuel may be injected through the orifice 39 from the oil chamber 41.

A device for stopping or interrupting the operation of the diesel hammer (to be referred to as the interruption device" hereinafter for brevity) comprises a stop valve 51 having a port 55 in communication with the fuel pump and a port 56 in communication with the nozzle, a lever 52 for closing the passage between the ports 55 and 56 and an arm 53 adapted to lock the lever 52 during the operation. The fuel tank 6 is intercommunicated with the fuel pump 7 through the fuel line 10. The fuel pump 7 is communicated with the port 55 of the stop valve 51 through the fuel line 11. The nozzle 8 is communicated with the port 56 of the stop valve 51 through the fuel line 54.

The interruption device will be described in more detail with reference to FIG. 14. The stop valve 51 has passage 57 formed coaxially of the valve body 59. The ports 55 and 56 are intercommunicated with each other through an oil chamber 58. The valve body 59 is fitted into a valve housing 60 by any suitable manner so that there exists no gap therebetween. A spool 61 which interrupts the communication between the ports 55 and 56 is slidably fitted into the hole or passage 57. A rod having its lower end securely fixed to the upper end of the spool 61 extends upwardly of the valve housing 60. A nut 63 into which is slidably fitted the rod 62 is screwed into the upper end of the valve housing 60. A spring 64 is interposed between the upper end of the nut 63 and the head of the rod 62. The shorter arm of the L-shaped lever 52 is pivotably fixed by a pivot 67 to the cylinder 1 above the stop valve 51. When a rope 68 whose one end is securely fixed to the free end of the longer arm 66 of the lever 52 is pulled down, the lever 52 rotates about the pivot 67. A projection 69 is extended from the side wall of the lever 52. An arm 53 having a rope 68 affixed to the free end thereof is pivotably fixed to the cylinder 1 above the lever 52 in such a manner that the arm 53 is normally applied with the force in the horizontal direction through a spring 70. When the lever 52 is rotated so that the arm 53 becomes horizontal, the leading end of the arm 53 engages with the projection 69. When the rope 68 is pulled so that the lever 52 is inclined, a projection 71 formed at the bend of the lever 52 pushes the rod 62 and the spool 61 downwardly so that the passage between the ports 55 and 56 is interrupted. In consequence, the fuel delivery is stopped. In this case, the arm 53 rotates to the horizontal position and engages with the projection 69, thereby preventing the return of the lever 52. In consequence, the diesel hammer remains deactivated. The spring 64 has a force stronger than that of the spring 70. A stopper 72 serves to determine the position of the lever 52 during the operation.

In the diesel hammer having the construction described hereinabove, when the ram 2 drops, it closes the suction-exhaust port 15 of the cylinder 1 and compresses the air adiabatically. Finally, the ram 2 strikes the anvil 3 so that a pile (not shown) is driven into the soil. The compressed air in the cylinder 1 is delivered to the fuel pump 7 through the air port 14, thereby actuating the pump 7. The fuel supplied from the fuel tank 6 is therefore forced into the fuel line 11 by the fuel pump 7 and is branched into two directions at the joint 9 so as to be delivered to the nozzle 8 through the fuel line 12 and to the nozzle 8' through the fuel line 13. The fuel delivered to the nozzles 8 and 8 is sprayed at an angle a relative to the line a and mixed with the air in the combustion chamber 5. Since the temperature of the air in the combustion chamber is elevated because of the compression, the sprayed fuel is burnt and the ram 2 is raised by the combustion gas pressure up to the initial position. Thus, one cycle of operation is accomplished. This operation may be continued as many times as desired until the pile is driven into a desired setting depth.

From the foregoing, it will be readily seen that fuel pump 7 is actuated by the air compressed when the ram 2 drops in the cylinder 1 and then the fuel is injected into the combustion chamber 5 through the nozzles 8 and 8. This means that the injection time may be made precisely coincident with the time the ram 2 strikes the anvil 3. That is, only a small portion of the fuel is injected when the ram 2 strikes the anvil 3 while the substantial portion of the fuel is injected immediately after the ram 2 strikes the anvil 3. In other words, no combustion occurs when the ram 2 drops in the cylinder 1, so that the pressure in the cylinder 1 is low, whereby the downward movement of the ram 2 will not be retarded or braked at all.

As described hereinabove, in the diesel hammer in accordance with the present invention only a small portion of the fuel is injected immediately before the ram 2 strikes the anvil 3 while the substantial portion is injected immediately after the ram 2 strikes the anvil 3 so that the ram 2 is raised from the position indicated by the chain lines in FIG. 8 to the position indicated by the solid lines during the fuel injection. In consequence, the volume of the combustion chamber 5 may be varied during the fuel injection, but the combustion chamber 5 is circular in cross section, the air in the cylinder 1 flows from the peripheral portion of the chamber 5 into the center thereof at a very high velocity as shown in FIGS. 8 and 9 when the ram 2 is raised during the fuel injection. Consequently, the fuel sprayed by the nozzles 8 and 8 is redirected toward the center of the combustion chamber 5. That is, when the fuel is sprayed as shown in FIG. 6, it is redirected as shown in FIG. 10 while when it is sprayed as shown in FIG. 7, it is redirected toward the center as shown in FIG. 11. That is, even when the volume of the combustion chamber 5 varies because ofthe upward movement of the ram 2, the fuel is mixed with the air in an efficient manner, whereby the best combustion may be accomplished.

Next the mode of operation of the fuel pump 7 described with reference to FIG. 12 will be described. The air compressed in the cylinder I acts upon the piston 26 through the port 14 and the passage 24, thereby raising the piston 26, the push rod 27, the guide 33 and the plunger 31. The valve 35 is opened so that the fuel is forced into the fuel lines II, I2 and 13 from the oil chamber 32 through the fuel line 10 and the passage 29, and then into the nozzles 8 and 8'. The fuelis delivered into the oil chamber 40 through the passages 46, 47 and 48 so that the needle valve 43 is opened against the spring 44. Thus, the fuel is delivered into the oil chamber 41 from which it is injected through the orifice 39 into the combustion chamber 5.

Since the temperature of the air in the combustion chamber 5 is elevated because of the compression, the fuel is immediately ignited.

The combustion product gas pressure acts upon the piston 26 so that the plunger 31 is raised. Therefore the fuel is injected into the combustion chamber 5 through the nozzles 8 and 8 so that the combustion may be continued. The pressure of the expanding gases acts upon the lower end of the ram 2, thereby lifting it to its initial position. When the ram 2 moves upwardly, it opens the suctionexhaust port I5, thereby exhausting the gases into the surrounding atmosphere. In this case, all of the piston 26, the push rod 27, the guide 33 and the plunger 31 are returned to their initial positions by the spring 34. Thus, the fresh air is introduced into the cylinder 1 through the suction-exhaust port when the ram 2 is raised to a predetermined height. The above-described operation may be cycled.

The fuel injection timing may be determined by the diameter (D cm) of the piston 26, the diameter (D. cm) of the plunger 31, the force (F kg) of the spring 34, the diameter (D cm) of the needle valve 43, the diameter (D cm) of the valve seat 45, the force (F: kg) of the spring 44 and the pressure of the air inside the cylinder 1.

That is, the following relation is held:

wherein P kg/cm is the static pressure of the air inside the cylinder 1 when the fuel is injected through the nozzles 8 and 8'. The force of the spring 34 is not taken into consideration.

The fuel injection interval is determined by the above described factors and the diameter (D, cm) of the orifice of the nozzle, the total mass of the movable parts such as the piston 26, the plunger 3l, the push rod 27, the guide 33, the valve 35, the nozzle needle valve 43, etc., the compression pressure and the pressure of the gases resulted from the combustion. However, it is empirically proved that when the mass of the movable parts is reduced as much as possible and the above described factors are so selected as to satisfy the relation (2) below, a required quantity of fuel may be injected into the cylinder 1 during a required fuel injection interval.

(I) /D;,) =300 to 500 (2) According to the present invention, the time the fuel injection is started may be almost made in coincidence with the time the ram 2 strikes the anvil 3 so that only one portion of the required fuel is injected immediately before the ram 2 strikes the anvil 3 while the substantial portion is injected immediately after the ram 2 strikes the anvil 3. Therefore, the present invention can eliminate one of the distinctive defects encountered in the prior art that the combustion occurs before the ram strikes the anvil, whereby the downward movement ofthe ram is retarded and the impact is reduced.

For this purpose, the pressure P(kg/cm-') (at which the fuel injection into the cylinder 1 is started and which is obtained from Equation I) is selected so as to be one-third to one half of the maximum air compression pressure. And the diameters are selected so as to satisfy the relations (2 Then, only one portion of the fuel is injected immediately before the ram 2 strikes the anvil 3 while the substantial portion is sprayed after the ram 2 strikes the anvil 3. This fuel injection method is not affected by a temperature of the diesel hammer, etc. Therefore, one of the defects encountered in the prior art may be eliminated.

According to the present invention, the fuel is sprayed continuously not instantaneously so that the combustion may be gradually continued so that the initial pressure of the expanding gases resulting from the combustion is low and the stresses due to this initial pressure of the cylinder 1, etc. may be reduced.

In the instant embodiment, the fuel injection system has I been described and shown as comprising one fuel pump 7 and two nozzles 8 and 8'. However, it will be understood that the present invention includes a fuel injection system comprising one fuel pump and one nozzle or a plurality offuel pumps and a plurality ofnozzles.

The diesel hammer provided with interruption device as shown in FIGS. I3 I5 will be described.

There are various methods for interrupting the delivery of the fuel from the fuel pump to the nozzle, thereby interrupting the operation of the diesel hammer. For examples, the following methods may be used;

a. the method for interrupting the delivery of the fuel between the fuel pump and the fuel tank;

b. the method in which a bypass valve is provided at the outlet of the fuel pump so as to bypass the fuel to the inlet of the fuel pump;

c. the method for mechanically stopping the fuel pump; and

d. the method for interrupting in which the air passage between the cylinder and the fuel pump, thereby deactivating the fuel pump.

In the methods (a) and (b), the resistance on the discharge side of the fuel pump is made almost zero so that the movable parts such as plunger, etc. are excessively accelerated, thus resulting in the damage. In the methods (c) and (d), the design, machining, assembly, etc. are very difficult.

These defects may be overcome by the interruption device as shown in FIGS. 13-15.

Referring to FIG. 14, when the lever 52 is in the position in dicated by the solid lines, the port 55 is intercommunicated with the port 56 so that the diesel hammer is driven. Therefore. when the ram 2 drops, the air in the cylinder I is compressed and by this compressed air, the fuel pump 7 is activated. The fuel delivered from the tank 6 is delivered to the nozzle 8 through the ports 55 and 56 by the fuel pump 7 so that the diesel hammer is driven.

To stop the diesel hammer, an operator pulls the rope 68. Therefore, the lever 52 rotates about the pin 67 to the position indicated by the chain lines so that the projection 71 of the lever 52 pushes down the rod 62 and the spool 61 connected thereto. Since the spool 61 is so precisely fitted into the oil chamber 58 that the gap therebetween is sufficiently small, the communication between the ports 55 and 56 is interrupted so that no fuel is delivered from the pump 7 to the nozzles 8 and 8 whereby the operation of the diesel hammer is stopped.

In this case, in response to the rotation of the lever 52, the arm 53 rotates under the force of the spring 70 until the arm 53 engages with the projection 69 of the lever 52 so that the lever 52 may be prevented from returning to the operative position indicated by the solid lines under the force of the spring 64. To return the lever 52 from the inoperative position to the operative position, the operator pulls the rope 68' connected to the arm 53, thereby rotating it toward the position indicated by the solid lines. Therefore, the lever 52, the rod 62 and the spool 61 may be returned to the positions indicated by the solid lines under the force of the spring 64 whose strength is stronger than that of the spring 70. Simultaneously. the arm 53 returns to its initial position. Therefore, the port 55 is communicated with the port 56 so that the fuel may be delivered to the nozzles 8 and 8. whereby the diesel hammer is driven.

FIG. I shows another embodiment of the operation interruption device in accordance with the present invention. An arm 53 is rotatably fixed to one side of the lever 52 and a spring 70 is so loaded as to apply the force to the arm 53, thereby rotating it in the clockwise direction. (The arm 53' pivotably fixed to one side ofthe lever 52 is normally so biased as to rotate in the clockwise direction by a spring 70). A stopper 73 is fixed to the cylinder I so as to hold the arm 53' in the horizontal position when it is rotated as the lever 52 rotates. When the rope 68 is pulled, the lever 52 is rotated so that the rod 62 is pushed downwardly while the arm 53' is rotated. Therefore, the leading end of the arm 53' engages with the cylinder I so that the return of the lever 52 is prevented. When the rope 68' is pulled, the arm 53' is disengaged (from the cylinder 1) so that the lever 52 is returned to its initial position.

When the port 56 is communicated to the fuel pump 7 while the port 55 is communicated with the nozzle 8, the operating pressure of the fuel pump 7 is generally in excess of the pressure for opening the valve of the nozzle 8 so that the force required for rotating the lever 52 becomes greater. But according to the present invention, the port 55 is communicated to the fuel pump 7 while the port 56 is communicated with the nozzle 8 so that the force required for rotating the lever 52 may be reduced.

When a returning or resetting mechanism of the arm 53 or 53' is not provided, the fuel pump is always operated. Therefore, there is a danger when the ram is dropped for the purposes other than that of starting the diesel hammer. But the present invention provides the mechanism for returning the lever 52 to its operative position so that the operation of the diesel hammer may be well safeguarded and become simple.

As described hereinabove, the present invention provides a diesel hammer in which a ram is slidably fitted into a cylinder having an anvil fitted into the lower end thereof; a combustion chamber circular in cross section is defined by the ram, the anvil and the inner wall of the cylinder; upon the cylinder are mounted a fuel tank and a fuel pump actuable by the air compressed when the ram drops so as to deliver the fuel received from the fuel tank; nozzles are diametrically opposed so as to inject the fuel into the combustion chamber; and the fuel delivered by the fuel pump actuated by the air compressed when the ram drops is sprayed into the combustion chamber through the nozzles. Therefore, the following advantages accrue from the present invention:

I. The substantial portion ofthe fuel is sprayed into the combustion chamber after the ram strikes the anvil so that the pressure in the cylinder may be reduced when the ram drops. Therefore, the downward movement of the ram is not retarded or braked at all so that the pile driving efficiency ofthe diesel hammer may be much improved.

II. The diesel hammer is not driven through mechanical cam means so that the movements of the movable parts are very smooth and their wear may be prevented. Therefore, the defects encountered in the prior art (FIG. 2) may be eliminated. When the fuel is sprayed at an angle relative to the center line connecting the opposing nozzles and the center of the combustion chamber, the fuel injection timing and the injection pressure may be adjusted by suitably adjusting the force of the nozzle valve spring 44.

Ill. The combustion after mixing of the fuel and air may be started at the best time which may be empirically determined. This condition will not vary irrespective of the operation time, the temperature, etc. Therefore, the defects encountered in the prior art (FIG. 1) can be eliminated.

IV. The air compressed in the combustion chamber may be smoothly delivered to the fuel pump. The air flows toward the center of the combustion chamber after the ram strikes the anvil so that the fuel sprayed at a predetermined angle through the nozzles may be concentrated toward the center so that the direction of the fuel injection may be optimized irrespective of the variation in volume of the combustion chamber. The fuel may be well mixed with the air at the center ofthe cylinder so that the best combustion occurs, whereby the efficiency of the diesel hammer and the pile driving force or impact may be much improved. In case of the diesel hammer wherein the anvil is fitted into the lower end of the cylinder and a ram is slidably fitted into the upper portion of the cylinder; upon the cylinder are mounted the fuel tank and a fuel pump in which the plunger is raised by the upward movement of the push rod guided by the piston actuated by the air compressed when the ram drops, thereby discharging the fuel delivered from the fuel tank; the nozzles are suitably arranged so as to spray the fuel delivered from the fuel pump; and the substantial portion of the fuel is sprayed immediately after the ram strikes the anvil.

V. The fuel is delivered to the nozzles from the fuel pump actuated by the air compressed in the cylinder when the ram drops. The nozzle has the needle valve. Therefore, only a small portion of the fuel is sprayed when the ram strikes the anvil while the remaining portion is sprayed after the ram strikes the anvil. Thus, the combustion will not occur during the downward stroke of the ram so that the pressure in the cylinder is low, whereby the downward movement of the ram will not be retarded or braked.

VI. The pressure of the expanding gases when the combustion is started is low, the stress acting upon the cylinder may be reduced.

VII. The push rod is guided by the stopper so that the upward movement of the push rod may be precisely controlled. The plunger is pushed upwardly by the push rod, and the cylinder is controlled in operation by the stopper so that the accurate and positive operation of the fuel pump may be ensured. In case of the diesel hammer in which the stop valve has in the fuel line communicating the fuel pump to the nozzle, the port for delivering the fuel from the fuel pump to one oil chamber and the port for delivering the fuel from the other oil chamber to the nozzle and the spool preciseiy fitted into the oil chamber, thereby interrupting the communication between the two ports; the lever is provided for inserting the spool of the stop valve into the oil chamber from the side of the port in communication with the fuel pump; and means for returning the lever to its initial position.

VIII. The defects encountered in the methods (a). (b), (c) and (d) described hereinabove can be eliminated. The ports are so communicated with the fuel pump and the nozzle respectively that the spool may be inserted into the oil chamber from the side of the port in communication with the fuel pump. Therefore, the force required for operating the lever may be reduced. Furthermore, whether the diesel hammer is in operative position or in inoperative position may be readily seen from the position of the lever. The operation of the diesel hammer becomes simple, and is safeguarded by said means for returning the lever to its initial position.

What is claimed is:

l. A diesel hammer comprising an anvil which is fitted into the lower end of a cylinder having an open upper end while a ram is slidably fitted into the upper portion of said cylinder. thereby defining a combustion chamber circular in cross section by said ram, said anvil and said cylinder; upon said cylinder are mounted a fuel tank and a fuel pump actuable by the air compressed when said ram drops in said cylinder; nozzles are arranged so as to spray the fuel into said combustion chamber; and the fuel delivered from said fuel tank is forced toward said nozzles by said fuel pump actuable by the air compressed when said ram drops.

2. A diesel hammer of the character described in claim 1 comprising the provision of means for making the fuel injection timing almost coincident with the time the lower end of the ram strikes the upper end of the anvil.

3. A diesel hammer of the character described in claim 1 wherein two fuel injection nozzles are disposed in a diametrically opposed relation with each other so as to spray the fuel into said combustion chamber from the opposed positions; the fuel delivered from said fuel pump is branched and delivered to said two nozzles; and the fuel is sprayed at a predetermined angle relative to the line connecting said two injection nozzles and the center of said cylinder.

4. A diesel hammer of the character described in claim 1 wherein said fuel pump comprises a piston actuable by the air, a push rod. a stopper for controlling the movement of said piston and also serving as a guide for said push rod, a plunger, etc.. whereby said plunger is pushed upwardly by the upward movement of said push rod caused by the movement of said piston so as to deliver the fuel; each of said nozzles has a needle valve which closes the fuel injection passage under the force of the spring and is opened by the fuel delivered; an air port is formed through said cylinder in order to deliver the compressed air from said combustion chamber to said fuel pump so as to actuate the same; and when said fuel pump is actuated by the air under pressure from said cylinder. the fuel delivered from said fuel tank is delivered to said nozzles by said fuel pump in such a manner that a substantial portion of the fuel may be sprayedinto said combustion chamber immediately after said ram strikes said anvil.

5. A diesel hammer of the character described in claim 1 wherein between said fuel pump and said nozzles is disposed a stop valve which has a port for delivering fuel from said fuel pump to one of the oil chambers and a port for delivering the fuel from said one oil chamber to said nozzles and a spool fitted into said oil chambers so as to interrupt the intercommunication between said two ports; a lever is suitably provided so as to insert said spool of said stop valve from the side of the port in communication with said fuel pump, thereby interrupting the intercommunication between said two ports; and means for returning said lever to its initial position. 

1. A diesel hammer comprising an anvil which is fitted into the lower end of a cylinder having an open upper end while a ram is slidably fitted into the upper portion of said cylinder, thereby defIning a combustion chamber circular in cross section by said ram, said anvil and said cylinder; upon said cylinder are mounted a fuel tank and a fuel pump actuable by the air compressed when said ram drops in said cylinder; nozzles are arranged so as to spray the fuel into said combustion chamber; and the fuel delivered from said fuel tank is forced toward said nozzles by said fuel pump actuable by the air compressed when said ram drops.
 2. A diesel hammer of the character described in claim 1 comprising the provision of means for making the fuel injection timing almost coincident with the time the lower end of the ram strikes the upper end of the anvil.
 3. A diesel hammer of the character described in claim 1 wherein two fuel injection nozzles are disposed in a diametrically opposed relation with each other so as to spray the fuel into said combustion chamber from the opposed positions; the fuel delivered from said fuel pump is branched and delivered to said two nozzles; and the fuel is sprayed at a predetermined angle relative to the line connecting said two injection nozzles and the center of said cylinder.
 4. A diesel hammer of the character described in claim 1 wherein said fuel pump comprises a piston actuable by the air, a push rod, a stopper for controlling the movement of said piston and also serving as a guide for said push rod, a plunger, etc., whereby said plunger is pushed upwardly by the upward movement of said push rod caused by the movement of said piston so as to deliver the fuel; each of said nozzles has a needle valve which closes the fuel injection passage under the force of the spring and is opened by the fuel delivered; an air port is formed through said cylinder in order to deliver the compressed air from said combustion chamber to said fuel pump so as to actuate the same; and when said fuel pump is actuated by the air under pressure from said cylinder, the fuel delivered from said fuel tank is delivered to said nozzles by said fuel pump in such a manner that a substantial portion of the fuel may be sprayed into said combustion chamber immediately after said ram strikes said anvil.
 5. A diesel hammer of the character described in claim 1 wherein between said fuel pump and said nozzles is disposed a stop valve which has a port for delivering fuel from said fuel pump to one of the oil chambers and a port for delivering the fuel from said one oil chamber to said nozzles and a spool fitted into said oil chambers so as to interrupt the intercommunication between said two ports; a lever is suitably provided so as to insert said spool of said stop valve from the side of the port in communication with said fuel pump, thereby interrupting the intercommunication between said two ports; and means for returning said lever to its initial position. 